[6.09] Secular Evolution of Meteoroid Streams

Gronchi and Milani (Cel. Mech. & Dynam. Astron. 71, 109,
1998) recently developed an analytical theory to compute the
secular evolution of planet crossing objects by averaging
the Hamiltonian on the fast angles also across the
singularity. With this theory Gronchi and Milani (Proc. of
ACM99, 1999) have computed proper elemets and proper
frequencies for NEAs, some comets and some good photographic
meteor orbits.

We use this theory to compute the secular evolution of a
meteoroid stream modelled in the following way: we eject a
number of particles about a perihelion passage of a given
comet, and then follow their evolution, making the
assumption that no close encounter with any planet actually
takes place.

We keep track of a number of dynamical quantities each time
the condition for actual crossing of the Earth's orbit is
satisfied; in particular we compute the values of the
geocentric quantities introduced for the purpose of stream
identification by Valsecchi et al. (Mon. Not. Royal Astron.
Soc. 304, 743, 1999), thus being able to characterise the
spreading of these quantities due to secular evolution.
Moreover we monitor, using the distance function of
Valsecchi et al. (1999), the separation of the stream from
its parent body. We then compare some of our simulated
streams with those actually observed.